Laravel 5中的原始SQL

I've got this code in my controller;

$sql = "SELECT * FROM `contracts`.`payments` as t1 
LEFT JOIN `postcodes`.`" . $postcode_lookup->dataset . "` AS t2 ON t1.`VendorZIP` = t2.`postcode` WHERE "; 

foreach ($input as $key => $value) {
    $sql .= "t2." . $key . " IN ('".implode("', '", $input[$key])."') OR ";
}

$sql = rtrim($sql, " OR ");

Which will return a working statement (when ran in SequelPro or PHPMyAdmin for example);

SELECT * FROM `contracts`.`payments` as t1 
LEFT JOIN `postcodes`.`201502_postcode` AS t2 ON t1.`VendorZIP` = t2.`postcode` 
WHERE t2.country IN ('L93000001', 'E92000001', 'M83000003', 'S92000003') 
OR t2.county IN ('E10000002') 
OR t2.gor IN ('Z', 'E', 'G', 'H') 
OR t2.locauth IN ('S12000033') 
OR t2.parlc IN ('W07000049')

How can I use raw queries in Laravel to run this in my application? and $payments = DB::raw($sql); doesn't do anything.